Abstract: The invention provides a novel association of polyvinylpyrrolidone with chlorin p6 and/or its salt with a pharmaceutically acceptable counter-ion and a method of preparation thereof. Preferably, the weight ratio of chlorin p6 and/or its salt with a pharmaceutically acceptable counter-ion to polyvinylpyrrolidone is contained within the range from about 1:1 to about 1:200. The association can be used as a photosensitizer in photodynamic therapy and/or diagnostics or for photochemical internalization of molecules as well as a photosensitizer in cosmetology. The invention provides also a pharmaceutical composition containing the novel association, a method of treating and diagnosing diseases by a dynamic phototherapy and a method of performing cosmetic procedures with the use of the novel association as a photosensitizer.